Resistance metal gathering machine



Jan. 24, 1961 E. c. BOOTH 2,969,455

RESISTANCE METAL GATHERING MACHINE Filed 0G11. 29, 1958 2 Sheets-Sheet 1 y wlmm Jan. 24, 1961 E. c. BOOTH 2,969,455

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United States Patent RESISTANCE METAL GATHERING MACHINE Eugene C. Booth, Bell, Calif., ssignor to Thompson Ramo Wooldridge, Inc., a corporation of Ohio Filed oef. 29, 195s, ser. No. 170,3s1 19 claims. (cl. 219-151) The present invention relates `to 'improvements 'in gathering or upsetting machines and lmethods of producin'g gathers on thermoplastic materials such as metals. More specifically, the invention relates to gathering machines which utilize electrical lenergy for heating a portion of the thermoplastic article for gathering the portion `and applying a compression load longitudinally of the article for gathering it in a transverse direction in the heated area. The specific invention also includes an improved apparatus and method for controlling the parameters effecting the gathering of the articles for improved characteristics of the article and improved control of the gathering operation. i A

In accordance with the present invention, articles formed of a material such as metal which is thermoplastic in :nature and will soften when heated, are subjected to a rlongitudinal compressive load to enlarge or gather an varea which is electrically heated. The electrical heating is achieved by impressing a Voltage on terminals in conductive contact with the article itself and the resistance of the article causes an increase in temperature 'over the ow path of the electrical current.

An important feature of the invention is the provision of making the factors of the gathering compressive force, the spacing between the electrical contacts, and the electrical voltage applied, independently variable and dependently operable in a machine, and providing improved relationship between these variable factors. Another important feature of the invention is to provide an apparatus and method whereby these factors are increased as a function of time before the article changes dimensions due to the gathering compressive force applied to it. A still further important feature is the provision of apparatus and a method for controlling the rate of change of these factors and the time period over which they change as a function of time and thereafter varying the factors as a function of the shortening or gathering of the material.

In one embodiment of the invention, an anvil is provided to support an article formed of a thermoplastic material such as metal, and a ram is provided to compress the article longitudinally against the anvil to apply a compressive force and cause a gathering of a section of the article. The section to be gathered is electrically heated by contacting the article with electrical terminals to cause a flow of electricity through a portion of the article whereby the resistance of the article will cause its temperature to increase over the path of electrical flow. The anvil may be used as one terminal and a sliding contact used as the other terminal. The electrical voltage impressed on the article is varied by a rheostat of a phase shift heat control. Means are provided in the form of three separate control pistons and cylinders to drive cams and operate followers to respectively control the pressure of the ram, to change the spacing between the electrical terminals, and to change the setting of the rheostat for varying the electrical voltage. Each of the control pistons and cylinders have rate adjustments and stroke acljustments, so that each of the factors ofv ram pressure, terminal spacing, and electrical voltage, ca'n be independently varied so that their rate of change as a function of time can be changed as to the rate and the 'total time of control. The control pistons and cylinders are mounted on a bar which moves with the ram so that the cams Will also be driven as a function of the compression or amount of gathering of the workpiece. The variable factors are first controlled as a function of the time and thereafter controlled as a function of gathering of the workpiece.

An object of the present invention is to provide an upsetting or gathering machine and a method for compressively gathering a portion of an article which is electrically heated. V

` kA further object of the invention is to provide improved machines and methods for improved control of the quality of an karticle which is compressively gathered and kfor controlling lthe factors which regulate the size of the gather, the rate of gather and the forces which must be applied. Y y

A'further object of theinvention is to provide improved machines and methods for applying and regulating the rate of application and time of application of compressive force to articles which are heated for a gathering action.

A still further object of the invention is to provide improved machines and methods for electrically yheating a portion of an article to which a compressive gathering force is to be applied and for controlling the area heated, the rate of Vapplication of the 'heat and the time period over which the heat is applied.

An important object of the invention is to provide an improved machine for gathering an article by heating a portion and applying compressive force wherein the factors of rate of change in force, rate of change in area to be heated, and rate of change in heat applied to the article are individually and controllably variable. A still further object of the invention is to provide a method and a machine wherein an article is gathered by applying a compressive force to a heated area and wherein the factors of amount of compressive force, area to be heated, and rate of heat increase are varied as a function of time and wherein the time period can be controlled for the individual factors.

Other objects and advantages will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings, in which:

Figure l is an elevational view shown in somewhat schematic form with parts in section of a machine for compressively gathering an article constructed in accordance with the principles of the invention, and illustrating the method of the invention;

Figure 2 is an illustration similar to Figure l and illustrating the machine with elements in different positions after a tirst time period of operation wherein certain factors are varied as a function of time; and,

Figure 3 is another view similar to Figures l and 2, and illustrating elements of the machine in another position during a subsequent time period of operation wherein certain factors are controlled as a function of the amount of gather of a workpiece.

As shown on the drawings:

Figure l illustrates a machine with the fluid ow system included and also with the electrical wiring shown. In Figures 2 and 3, the fluid conduits and certain portions of the wiring are omitted for clarity, inasmuch as these iigures are a reproduction of Figure l, but the figures show the parts in different positions at different periods of the operational cycle.

Basically, the machine includes an anvil 6 having an upper surface 8 for supporting a workpiece 10. A

12 is positioned to move in a path toward the anvil 6 for applying a compressive force to the workpiece in a longitudinal direction to cause gathering of the workpiece in a transverse or lateral direction. In the form illustrated, the workpiece is gathered at its lower end 14. To obtain gathering in this area, the workpiece is heated. The workpiece is formed of a thermoplastic material, such as metal, which will become plastic when heated to a certain temperature.

In the form illustrated, the source of heat for the workpiece is derived from electrical energy applied in the form of a current owing through the material of the workpiece. The workpiece is engaged by spaced electrical contacts and a voltage impressed across the contacts with the resistance of the material of the workpiece causing it to increase rapidly to a temperature to plasticize the material.

The anvil 6 acts as the lower terminal and the upper terminal is formed by a scissors block 16, which is so termed because of having opposing parts 18 and 20 which are movable laterally in engagement with the workpiece l0. At the inner ends of the parts 18 and 20 are contact members 22 and 24 which may be in the form of electrical conducting members or brushes.

Electrical energy is applied by transformer 26 and leads 28 and 30 from the secondary coil of the transformer are connected respectively to the anvil 6 and to the contacts 22 and 24. One side of the primary coil of the transformer 26 is connected by a tap switch 157 to a lead 34 leading to a supply source o-f electricity, and the other side is connected to a lead 32 which forms a circuit from a phase shift heat control 38 connected to the supply source of electricity by lead 156.

Voltage to the primary coil is changed by a variable resistor or rheostat 40 which is varied in a manner which will later be described. The number of turns in the primary may be changed by tap switch 157.

The electrical contacts 22 and 24 are located at a location along the workpiece 10 spaced from the anvil 6 which forms the other lcontact. This spacing is varied and for this purpose, the contacts 22 and 24 are carried on rods 42 and y44 mounted on a cross head 46 connected to a piston rod 48 which is secured to a piston 50.

The piston 50 controls the position of the contacts 22 and 24 and is slidably located in a contact control cylinder 52. Fluid lines 54 and 56 connect to opposite ends of the cylinder 52 to lcontrol the position of the piston 50 therein. The flow of uid to the cylinder is controlled by a yilow regulating tracing valve 58 which is operated by a contact position control cam 60. A pressure supply line 62 for the fluid pressure connects to the valve 58 and the position of the plunger 64 for the valve controls the rate of ow through the valve into the head end 66 of the cylinder SZ. The tracing valve is provided with an exhaust line 68 to permit the escape of fluid from the other end of the cylinder 52 through the line 54.

The cam 60, during upsetting operation of the machine, will move to the left, as shown in Figures 1, 2 and 3, and for this purpose it is provided with a rack 70 extending horizontally and secured at its upper side. The rack is driven by the pinion 72 which is rotated by a vertical rack 74. The vertical rack is attached to the lower end of a piston rod 76 connected to a piston 78. The piston is slidably housed in a contact controlling cylinder 80.

For moving the piston 78 downwardly in the cylinder 80, a fluid line 82 connects to the upper end of the cylinder and supplies uid through an adjustable flow valve 84. Fluid escapes from the lower end of the cylinder through an exhaust line 86. The piston can be raised within the cylinder by admitting uid through the exhaust line 86 and venting the line 82. In operation of the machine, the piston 78 is moved downwardly at a controlled rate of speed by the adjusted opening of the valve 84 and the line 82 is supplied with fluid pressure from a main supply line 88 through a directional control valve 90 or from an independent supply source with a directional control valve corresponding to valve 90.

The independent source may supply a dilerent fluid to cylinder 80 than the fluid that is supplied to cylinder 130. The shape of the surface 92 of the contact position control cam 60 will determine the rate of movement of the `contacts 22 and 24 away from the anvil 6. inasmuch as the piston 78 moves downwardly at an evenly timed rate, the contacts will move apart as a function of time and also as a function of the shape of the surface 92 of the cam 60.

The piston rod 76 carries a laterally extending arm 94 provided with an opening on the end to hold it in alignment with a guide rod 96 which carries a stop 98. The stop 98 is adjustable on the guide rod 96, and when the lateral arm 92 strikes the stop, the downward movement of the piston 78 will be terminated. Thus the stop 98 controls the stroke of the piston and the time period of operation of the mechanism for separating the electrical contacts.

The piston 78 and its cylinder 80 are mounted on a horizontally extending bar 100. As will later be explained, this bar remains stationary during the movement of the piston 78 until after it reaches its stop, and will then move downwardly as a function of the movement of the ram 12, inasmuch as the bar 100 is mounted on the ram.

The rheostat 40 which controls the voltage across the contacts 22, 24 and the anvil contact 6, is driven in rotation by a rack 102. The rack has a follower 104 which is in engagement with a surface 106 of a voltage controlling cam 108. A spring 110 is positioned to insure continued engagement between the follower 104 and the cam surface 106.

The cam 108 is carried on the lower end of a piston rod 112 connected to a piston 113 slidably mounted in a voltage controlling cylinder 116. The cylinder 116 is supplied with fluid pressure at its upper end from the line 82 through an adjustable iiow valve 118, which controls the rate of movement of the piston 113 with respect to time. Fluid escapes `from the lower end of the cylinder through the line 86 and the cylinder may be raised by admitting pressurized fluid through the exhaust line 86.

The piston rod 112 carries a laterally extending arm 120 which slides on a guide rod 122, and which engages an adjustable stop 124 on the lower end of the stroke of the piston 113. This adjusts the period of time of operation of variation of the rheostat as a function of time. The piston 113 and its cylinder 116 are also mounted on the bar 100 so that the voltage controlling cam 108 will move downwardly with the bar and with the ram, as a function of the position of the ram.

The ram 12 is part of a piston rod 126 connected to a piston 128. The piston is slidably mounted in a ramoperating cylinder 130. Fluid is supplied to the upper end of the cylinder through a line 132 to form a power operator for driving the ram. Fluid escapes from the lower end of the cylinder 130 through an exhaust line 134. Fluid for operating the ram piston 128 is obtained from a line 136 which is also supplied through the control valve 90 from the supply line 88. The fluid line 136 leads through a variable control Valve 138 which is regulated by a cam 140 to control the pressure or force applied against the ram 12. The force is, of course, dependent upon the rate at which pressurized nid is admitted to the upper end of the cylinder 130.

The Valve 138 is of the conventional pressure reducing type and the pressure at which iiuid is admitted into the line 132, depends upon the valve spring pressure. .This is controlled by a plunger 142, which compresses the valve controlling spring. The plunger carries a follower 144 which is held in engagement with the surface 146 of the cam 14@ byfthe valve spring.

The cam 5140 is moved downwardly vertically to control the pressure of the valve 138 and for this purpose is carried on a piston rod 150 secured to a piston 152. The piston is slidably contained in a cylinder 154. `Fluid is supplied to the upper end of the cylinder through a variable throttle valve 156 which is supplied from the vline 82. Fluid escapes through the bottom of the cylinder 154 through the exhaust line 86. The piston rod 150 carries an arm 151 which strikes an adjustable stop nut 155 on a rod 153 to limit the rod stroke. As will be understood, the shape of the cam 140 is for purposes of illustration only and different shapes may be employed. T he variation or change of the application of force on the workpiece is controlled as a predetermined function of time, bythe shape of the cam surface 146.

Following the sequence of operation in Figures 1, 2 and 3, a workpiece is first placed in position beneath the ram 12 and on the surface 8 of the anvil 6. The scissors blocks 18 and 20 carrying the contacts 22 and 24 are moved against the workpiece to form a circuit between the contacts 22 and 24 and the contact formed by the anvil 6. To start the machine, the control switch for voltage control 38 is closed and at the same time the control Valve 90 is opened. When the switch is closed, an electrical current will ow to heat a short transverse portion at thelower end 14 of the workpiece due to the resistance offered by the workpiece to the path of flow of electricity between the contacts. When the control valve 90 is opened, the contact position control piston 78 begins to descend and the contact control cam 60 begins to move to the left to admit fluid to the lower end of the cylinder 52. This slides the electrical contacts 22 and 24 on the workpiece, changing the flow path for the electricity and gradually changing the length of the transverse area of the workpiece which is heated.

At the same time, the piston 113 begins moving downwardly and the voltage control cam 108 turns the rheostat 40 to change the voltage impressed across the terminals and change the electrical energy supplied to heat the workpiece.

Alsoat the same time, the piston 152 begins to descend to move the cam 140 downwardly and change the pressure of the iluid which is supplied through line 132 to the upper end of the cylinder 130.

Thus, simultaneously, and as a function of time, the distance between the electricalcontacts will change, the electrical energy supplied for heating the workpiece will change, and the force applied to the ram 12 will change. The time rate of change of each of these factors is in dividually adjustable by regulation of the variable flow valves 84, 118 and 156.

The total time period over which these factors are changed as a function of time is also adjustable by varying the position of the stops 98, 124 and 155.

At the end of a first time period during which time the factors of force applied to the ram, spacing between the electrical contacts and electrical energy applied to the workpiece, are varied as a function of time, the ram 12 begins descending because the pressure in the upper end of the cylinder will have built up suiciently and the material of the workpiece will have become plastic. During the next period of time when the ram is descending, the above factors will vary as a function of the descent of the ram. They will thus vary as a function of the foreshortening'of the workpiece 10 or of the expansion or gathering of the portion 14 of the workpiece which is gathered. This is accomplished by the lowering of the entire mechanism for controlling the cams on the horizontal bar 100 which is secured to the ram. Cams 108 and 140 for controlling the voltage and the pressure applied to the ram, lower with respect to their followers and the rack 74 lowers to rotate the pinion 72, although the cam 6 60 remains stationary, but isdriven to the lett, as shown in the drawings.

The position of the relative elements at the end of the rst time period after the factors have been varied for the first period ottime as a function of time is illustrated in Figure 2.

The position of the elements at the end of the second period of time during which the variable factors have been varied as a function of the upsetting of the workpiece, is shown in Figure 3. It is to be noted that at this point the lower end14'of the workpiece is gathered to form the expanded portion.

Thus it will be seen that I have provided an improved gathering machine land method which meet the objectives and advantages hereinbefore set forth. The controllable variables of pressure applied by the ram, distance between electrical contacts and voltage applied to the workpiece are regulatable as a function of time before upsetting of the workpiece occurs. During this period both the time rate and the total period of control of each of the factors are individually variable to obtain control for an in1- proved product and improved method of manufacture of the product. The shape of the control cams also permits variation of the rateof change of the factors during the second time period when they vary as a function of the amount of upset of the workpiece.

I have, in the drawings and specification, presented a detailed disclosure of the preferred embodiments of my invention, but it is to be understood that I do not intend to limit the invention to the specific form disclosed but intend to cover all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by my invention.

I claim as my invention:

1. The method of gathering a thermoplastic article which comprises the steps of heating a short length of a transverse area of said article to a plastic state, progressively changing the length of the transverse heated area while the cross-sectional area of said transverse area remains the same, subsequently increasing the cross-sectional area of said transverse heated area by compression loading the article in a-longitudinal direction, and progressively continuing to increase the length of the heated area after starting to increase the cross-sectional area by said compression loading.

2. The method of upsetting a thermoplastic article which comprises the steps of heating a short length of a transverse area of said article to a plastic state, progressively changing the length of the transverse heated area while the cross-sectional areaof said transverse area remains the same, and subsequently increasing the crosssectional area of said transverse heated area by compression loading the article in a longitudinal direction.

3. The method of increasing the cross-sectional area of a workpiece which comprises heating a short cross-sectional area of the workpice, heating progressive areas to increase the length of the heated portion of the workpiece as a function of time, increasing the cross-sectional -area of the heated area at the end of a predetermined time period, and subsequently heating additional lengths of cross-sectional area adjacent the first heated lengths as an inverse function of the length of said workpiece.

4. The method of enlarging transversely an area of an article which comprises the steps of applying a continuous electrical voltage across a length of an article to be enlarged t0 heat a transverse section of the article, increasing the electrical voltage applied to the article as a function of time, applying a longitudinal upsetting force to the article, and increasing the longitudinal force applied concurrently with the increase in electrical voltage.

5. The method of enlarging transversely an area of an article which comprises the steps of applying an electrical voltage across a length of an article to be enlarged to heat a transverse section of the article, changing the electrical voltage applied to the article as a function of time, subsequently enlarging the heated length with the application of a longitudinal upsetting pressure to the article, and changing the application of electrical voltage during said enlarging step as a predetermined function of the length of the article so as to control the transfer of heat energy to the article.

6. A power-operated gathering machine comprising in combination a surface for supporting a workpiece for a gathering operation, a ram movable in a path toward said supporting surface, power means for driving said ram, said power means operatively to apply longitudinal pressure to the ram over a range of pressures, and control means connected to said ram power means for controlling the pressure applied to the ram and operative to increase the pressure applied to said ram over a period of time at a predetermined rate as a predetermined function of time before the ram builds up suicient pressure to upset the workpiece.

7. The method of upsetting a thermoplastic article which comprises heating -a transverse area of the material to a plastic state, applying a changing compression loading force on the material longitudinally thereof to cause transverse upsetting, and controlling the change of the application of longitudinal force on the article as a predetermined function of time.

8. The method of upsetting a metal article which comprises heating a transverse section of the article to transform the section to a relatively thermoplastic state, applying a longitudinal pressure on the article, and increasing the longitudinal pressure during a time period at a predetermined rate and as a predetermined function of time before the material expands from the longitudinal pressure. Y

9. The method of transversely enlarging a portion of an article which comprises heating a transverse section which is to be enlarged, applying a longitudinal force to the article at the ends, increasing the longitudinal force as a function of time before the section enlarges, and after the section begins to enlarge changing the longitudinal force as a predetermined function of the amount which the article is longitudinally shortened due to the enlarging.

l0. The method of upsetting an article formed of a material capable of becoming plastic when heated which comprises applying electrical voltage at a transverse area to be upset along the article whereby the resistance of the material of the article will cause an increase in temperature; applying a longitudinal compressive force to the article for gathering the heated portion; simultaneously increasing the voltage applied to the article, increasing the path of travel of the electrical current through the article due to the impressed voltage, and increasing the compressive force applied to the article as a predetermined function of time during a first time period; and subsequently changing the path of electrical current, changing the voltage applied, and changing the compressive force during a second time period as a predetermined function of the foreshortening of the article due to the upsetting of the heated portion.

11. A gathering machine comprising in combination an anvil, a power-actuated ram movable in opposition to the anvil for gathering an article therebetween, means for applying an electrical voltage to an article between the ram and anvil through a path whereby the resistance of the article will cause a temperature increase to convert a portion of the article to a relatively plastic character, means for gradually increasing the electrical path through the article whereby an increasing portion takes on said plastic characteristic prior to movement of the ram toward the anvil, and power means for causing the ram to apply compressing pressure to the article to move it toward the anvil.

12. A machine for upsetting a thermoplastic article comprising in combination means for heating a thin, transverse zone of an article, means for applying a longitudinal pressure to the article whereby a compressive force will be attained for gathering the material in the heated zone, means for operating said pressure applying means, and means for heating areas adjacent the heated zone to change the length thereof prior to said operating means compressing the article to upset said heated zone.

13. A mechanism for enlarging a portion of an article of thermoplastic material which comprises means for heating an article Vover 'a transverse area, means for applying a longitudinal pressure to the ends of the article for laterally enlarging the heated zone of the article, means connected to said heating means and operative to increase the length of the zone heated on the article, a first means connected to said length increasing means for increasing the length of the Zone before the material is enlarged as a function of time, and second means connected to said length increasing means and increasing the length of said zone after the article begins enlarging as a function of the shortening of the `article with enlargement in a transverse direction.

14. An electric gathering machine comprising in combination an anvil positioned to support a workpiece to be upset, a ram positioned to move in opposition to the anvil for applying longitudinal upsetting pressure to the workpiece, power means for moving the ram, a device for heating a transverse portion of said workpiece, first means for causing the heating means to increase the length of transverse portion which is heated over a rst time period before the ram is moved by said power means, and second means for further increasing the length of said transverse portion which is heated over a second time period after said ram is being moved by said power means.

l5. An upsetting machine comprising in combination a fixed anvil for supporting a workpiece to be laterally upset, a power-operated ram positioned to move in a path towards said anvil for applying longitudinal pressure t0 said workpiece, a pair of electrical contacts positioned to engage said workpiece at longitudinally spaced locations for causing a flow of electricity in the workpiece whereby the electricity will increase the temperature to plasticize the workpiece over the electrical flow path, operating means for driving said ram, means for gradually increasing the flow of electricity through said contact means, and means for controlling the operation of said operating means and said electrical flow increase means and causing operation of the electrical flow increase means for a period of time prior to the operation of said operating means whereby the electrical flow is gradually increased before the workpiece is upset.

16. A mechanism for upsetting an article of thermoplastic material comprising an anvil for supporting a workpiece, a ram for applying a longitudinal upsetting pressure to said workpiece, power means for driving said ram, control means connected to said power means for controlling the factors of rate of increase of power applied by the rarn and the time period over which the rate changes independent of movement of the ram, and adjustment means for varying the operation of said control means as to at least one of said factors.

17. A mechanism for upsetting an article of thermoplastic material comprising in combination an anvil for supporting a workpiece, a ram for applying a longitudinal upsetting pressure to force said workpiece against said anvil, a pair of spaced contacts positioned to engage said workpiece, means for progressively separating the contacts to increase the path of electrical travel along said workpiece, control means for Said separating means for controlling the factors of rate of change of separation and time period over which the contacts are changed independent of movement of the ram, and adjustment means for varying the operation of said control means as to at least one of said factors.

,18, A. mechanism for upsetting an article by an axial compressive force comprising in combination an anvil for supporting a workpiece of thermoplastic material, a ram for applying longitudinal upsetting pressure to said workpiece, electrically energized heating means for heating a transverse portion of the workpiece, means connected to said heating means and operative to increase the voltage, control means connected to the voltage increase means for controlling the factors of rate of increase of electrical energy and the time period over which the rate of change occurs, and adjustment means for varying the operation of said control means as to at least one of said factors.

19. A power-operated gathering machine which comprises an anvil, a ram movable in a path to compress an article against the anvil, a piston slidably contained in a cylinder and connected to drive said rain, a pair of electrical contacts positioned to engage the workpiece, a piston connected to one of said contacts and slidably contained in a cylinder for moving the contact away from the other contact, electrical energizing means connected to said contacts and operative to vary the electrical energy applied, a valve and cam connected to control the movement of the piston for operating the electrical contacts, a valve and cam combination connected to operate lthe electrical energy supply means, a valve and cam combination connected to control the rate of movement of the piston for the ram, individual pistons and cylinders each connected to move said cams, and a common mounting means supporting said pistons and cylinders and mounted to move with the piston for operating the ram whereby said cams may be moved individually by said control pistons and may be moved as a group by operation of the ram operating piston whereby said cams may be moved as a function of time and as a function of movement of the ram operating piston.

References Cited in the le of this patent UNITED STATES PATENTS 

